1. Field of the Invention
The invention relates generally to bracing devices and particularly to load stabilization devices capable of preventing the incidental and often injurious shifting of cargo within a freight-carrying car such as a truck trailer or train car.
2. Description of the Prior Art
Devices known as dunnage bars have long been used to brace or support cargo items within cargo carrying areas of land, air and sea vehicles. Such devices are particularly required where partial loads are contained within train boxcars, truck trailers and the like, the free space within such vehicles allowing the potentially damaging shifting of cargo on movement of the vehicle. Containerized freight disposed within a truck trailer, for example, is subject to forward/rearward shifting during normal operation of the vehicle. A dunnage device can thus be used to brace a cargo item against shifting movement along the longitudinal axis of the vehicle, that is, along the direction of motion thereof. Further, a dunnage bar or similar device can be used to brace multiple cargo elements within a portion of a storage hold by disposing one or more dunnage bars transversely of the storage hold to effectively form a temporary restraining wall within the cargo hold to prevent shifting of cargo contained therein.
Dunnage devices are described by Teachout in U.S. Pat. No. 969,002 and by Sharp in U.S. Pat. No. 3,214,027, these devices being used in environments similar to that for which the present invention is intended. Astrom, in U.S. Pat. No. 891,897, describes a trench brace which is utilized to shore timbers and the like in excavations, the bracing function thus described being similar to the bracing function of a dunnage device and thus falling within the intended use environment of the structure of the present invention. Similar load stabilization and bracing devices are described in the patent literature and are available for use. However, prior art structures have typically been either expensive and difficult to use as well as generally inappropriate for all but a few bracing situations. The more recent cargo bracing or bulkhead systems are structurally complex and difficult to assemble by a single worker, such prior devices and systems also often fail to provide the necessary compressive forces needed to prevent the shifting and tipping of cargo contained within a freight storage compartment of a moving vehicle. The present invention provides an effective dunnage brace capable of resisting shifting, sliding and tipping movement of cargo items, the present structure being relatively inexpensive, light in weight and structurally simple while exhibiting maximum strength and providing maximum stability to a load which would otherwise be loosely contained within a cargo hold and therefore subject to potentially damaging movement on movement of the vehicle. Accordingly, the invention intends improvement over the structures of the prior art and exhibits advantages thereover as will be more fully referred to hereinafter.